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Phenomenology of a PseudoScalar Inflaton
 Naturally Large Nongaussianity,” JCAP 1104 (2011) 009, arXiv:1102.4333
"... ar ..."
Dynamics with Infinitely Many Derivatives: The Initial Value Problem
, 2008
"... Differential equations of infinite order are an increasingly important class of equations in theoretical physics. Such equations are ubiquitous in string field theory and have recently attracted considerable interest also from cosmologists. Though these equations have been studied in the classical ..."
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Cited by 20 (0 self)
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Differential equations of infinite order are an increasingly important class of equations in theoretical physics. Such equations are ubiquitous in string field theory and have recently attracted considerable interest also from cosmologists. Though these equations have been studied in the classical mathematical literature, it appears that the physics community is largely unaware of the relevant formalism. Of particular importance is the fate of the initial value problem. Under what circumstances do infinite order differential equations possess a welldefined initial value problem and how many initial data are required? In this paper we study the initial value problem for infinite order differential equations in the mathematical framework of the formal operator calculus, with analytic initial data. This formalism allows us to handle simultaneously a wide array of different nonlocal equations within a single framework and also admits a transparent physical interpretation. We show that differential equations of infinite order do not generically admit infinitely many initial data. Rather, each pole of the propagator contributes two initial data to the final solution. Though it is possible to find differential equations of infinite order which admit welldefined initial value problem with only two initial data, neither
Oneloop corrections to a scalar field during inflation
 SUBMITTED TO: JCAP
, 2008
"... The leading quantum correction to the power spectrum of a gravitationallycoupled light scalar field is calculated, assuming that it is generated during a phase of singlefield, slowroll inflation. ..."
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Cited by 18 (8 self)
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The leading quantum correction to the power spectrum of a gravitationallycoupled light scalar field is calculated, assuming that it is generated during a phase of singlefield, slowroll inflation.
Effects of ScaleDependent NonGaussianity on Cosmological Structures
, 2008
"... Abstract: The detection of primordial nonGaussianity could provide a powerful means to test various inflationary scenarios. Although scaleinvariant nonGaussianity (often described by the fNL formalism) is currently best constrained by the CMB, singlefield models with changing sound speed can hav ..."
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Cited by 6 (1 self)
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Abstract: The detection of primordial nonGaussianity could provide a powerful means to test various inflationary scenarios. Although scaleinvariant nonGaussianity (often described by the fNL formalism) is currently best constrained by the CMB, singlefield models with changing sound speed can have strongly scaledependent nonGaussianity. Such models could evade the CMB constraints but still have important effects at scales responsible for the formation of cosmological objects such as clusters and galaxies. We compute the effect of scaledependent primordial nonGaussianity on cluster number counts as a function of redshift, using a simple ansatz to model scaledependent features. We forecast constraints on these models achievable with forthcoming data sets. We also examine consequences for the galaxy bispectrum. Our results are relevant for the DiracBornInfeld model of brane inflation, where the scaledependence of the nonGaussianity is directly related to
Stable bounce and inflation in nonlocal higher derivative cosmology
 PREPARED FOR SUBMISSION TO JCAP
, 2012
"... One of the greatest problems of primordial inflation is that the inflationary spacetime is pastincomplete. This is mainly because Einstein’s GR suffers from a spacelike Big Bang singularity. It has recently been shown that ghostfree, nonlocal higherderivative ultraviolet modifications of Ei ..."
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Cited by 4 (1 self)
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One of the greatest problems of primordial inflation is that the inflationary spacetime is pastincomplete. This is mainly because Einstein’s GR suffers from a spacelike Big Bang singularity. It has recently been shown that ghostfree, nonlocal higherderivative ultraviolet modifications of Einstein’s gravity may be able to resolve the cosmological Big Bang singularity via a nonsingular bounce. Within the framework of such nonlocal cosmological models, we are going to study both sub and superHubble perturbations around an inflationary trajectory which is preceded by the Big Bounce in the past, and demonstrate that the inflationary trajectory has an ultraviolet completion and that perturbations do not suffer from any pathologies.
Features and nongaussianity in the inflationary power spectrum
, 805
"... I summarize recent work on (1) constraining spikelike features in the cosmic microwave background (CMB) and large scale structure (LSS); (2) nonstandard Friedmann equation in stabilized warped 6D brane cosmology, with applications to inflation; and (3) nonlocal inflation models, motivated by string ..."
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I summarize recent work on (1) constraining spikelike features in the cosmic microwave background (CMB) and large scale structure (LSS); (2) nonstandard Friedmann equation in stabilized warped 6D brane cosmology, with applications to inflation; and (3) nonlocal inflation models, motivated by string theory, which can yield large nongaussian CMB fluctuations.
UVIR quantum entanglement and its imprints on the
, 707
"... new mechanism for nonlocality from string theory: ..."
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Preprint typeset in JHEP style HYPER VERSION Dynamics with Infinitely Many Derivatives: The Initial Value Problem
, 2008
"... Abstract: Differential equations of infinite order are an increasingly important class of equations in theoretical physics. Such equations are ubiquitous in string field theory and have recently attracted considerable interest also from cosmologists. Though these equations have been studied in the c ..."
Abstract
 Add to MetaCart
Abstract: Differential equations of infinite order are an increasingly important class of equations in theoretical physics. Such equations are ubiquitous in string field theory and have recently attracted considerable interest also from cosmologists. Though these equations have been studied in the classical mathematical literature, it appears that the physics community is largely unaware of the relevant formalism. Of particular importance is the fate of the initial value problem. Under what circumstances do infinite order differential equations possess a welldefined initial value problem and how many initial data are required? In this paper we study the initial value problem for infinite order differential equations in the mathematical framework of the formal operator calculus, with analytic initial data. This formalism allows us to handle simultaneously a wide array of different nonlocal equations within a single framework and also admits a transparent physical interpretation. We show that differential equations of infinite order do not generically admit infinitely many initial data. Rather, each pole of the propagator contributes two initial data to the final solution. Though it is possible to find differential equations of infinite order which admit welldefined initial value problem with only two initial data, neither